Hypomyces luteovirens (Pyrenomycetes Ascomycota)
Hypomyces luteovirens parasitizes mushrooms belonging to the genus Russula. It changes both the colour and the general appearance of the infected mushrooms. Gills of the host are supressed and, in their place, the parasite produces thousands of tiny raised spherical structures (perithecia) over the surface of the parasitized hosts. These are especially noticeable on the stalk which also turns yellow to green to olive. Widespread but not common. The final product is the modfied mushrooms you see above that is an intimate associationof host and parasite. A mycological mix made up of part host and part parasite in which the perithecia of the host are embedded is called a pseudostroma.